hernia, etc. By it we understand a discharge of the entire intestinal contents by the mouth, which occurs when the distended intestines have lost their power of contraction, and no longer oppose abdominal pressure, which causes the contents of the bowels to be expelled by vomiting.

The fatal termination is hastened by the appearance of fulminating purulent peritonitis, which sets in as soon as the contents penetrate the intestinal wall and spread themselves over the peritoneal surface.

In proportion as the hyperemia of the mucous capillaries assumes, instead of a temporary, a more permanent character, the blood vessels cease to absorb the nutritive material, as far as normal digestion and blood formation is concerned. For this reason absorption is greatly impaired in diseases of the heart and lungs, when there is a permanent hyperæmia of the mucous membrane of the digestive tract. The absorption of chyle is also somewhat disturbed, as the flow of chyle depends upon the precision and regularity of a number of factors, such as an intact epithelium, a regular contraction and erection of the intestinal villi, an undisturbed and powerful peristalsis, and an exact and well-timed filling of the blood vessels. It is clear that every serious inflammation must interfere with the action of one or more of these factors. A normal condition of the mesenteric glands is also necessary to the further progress of the absorbed chyle. An inflammatory, cancerous, or tuberculous intumescence of these glands imperils the process of absorption, just in proportion as the intra-glandular lymphatics are more or less effectively obstructed.

Marasmus, Defective Nutrition.

The evil effects of any serious disturbance of nutrition in the digestive tract are apparent to all: hollow eyes, thin and emaciated limbs, pallid and withered skin,-such are the sequelae of this condition. Marasmus or the result of a prolonged loss of food, has already been sketched, where especial stress was laid upon the diminished quantity of blood and the loss of flesh.

Physiology teaches us how the hungry body, robbed of its food, subsists at the expense of the muscles and fat, until, after the lapse of two weeks, it can no longer, by preying upon itself, avert the deadly suspension of sensibility, and thus perishes, of complete exhaustion.

DISTURBANCES IN BLOOD CORPUSCLE FORMATION.

The most important constituents of the blood are the red blood corpuscles. They alone possess the power to take up oxygen in the lungs, and conduct it in loose chemical combination to the tissues of the body. This power of the red blood corpuscles is due to hæmoglobin, a peculiar reddish-yellow substance which they contain. Hæmoglobin is readily resolved, by the action of alkalies and acids, into an albuminous body, globulin, and into the coloring matter of the blood, in its restricted sense, hæmatin. This separation is more rapidly accomplished by ozone, especially with high temperature. When we picture to ourselves the unceasing action of the inspired particles of oxygen upon the red blood corpuscles, we can comprehend the rapid changes which the molecules of hæmoglobin undergo in the body, changes whose magnitude may be estimated by a comparison with the quantity of pigment secreted by the bile. No one now questions that bilirubin is identical with transformed hæmatin, but nothing is known of what becomes of the globulin. At any rate the disintegration of the hæmoglobulin calls for a rapid restoration of the blood, and just here our knowledge of the formation of blood is completely at fault. We do not know to what degree the hæmoglobin-changes are identical with those of the red blood corpuscles, nor whether the blood corpuscle yields up its hæmoglobin individually; whether there is a shedding of hæmoglobin, or whether for each amount of bilirubin secreted in the bile a corresponding number of red blood corpuscles are withdrawn from the circulation.

Nature displays a certain extravagance with red blood corpuscles, and slight losses of blood seem easily repaired. Still we meet here with individual differences, and the formation of the red blood corpuscles is, and will doubtless remain, one of the most difficult problems of our science. Little is known of the remote conditions or the locality and the histological process concerned in the origin of the red blood corpuscles.

In the red marrow of the bones and in the splenic pulp of the mammalia, we find nucleated red blood corpuscles, which resemble exactly embryonic corpuscles (hæmatoblasts). Processes of nuclear and cell division may be easily observed in these cells. I also believe I have demonstrated that these cells, by expulsion of their nuclei and mechanical remodeling

of their shape, are converted into the well known bi-concave, non-nucleated discs.

According to the above, the production of the red blood corpuscles would be the function of the splenic pulp and the red marrow of bones, and disturbances in the formation of red blood corpuscles would be referable to disturbances in the above sources a hypothesis which entirely agrees with observed pathological facts. So we shall for the present consider essential anæmias as disturbances of splenic or medullary hæmatosis, without attempting an exact definition of the process or dwelling upon the post-mortem studies relating

thereto.

Essential Anæmias.

An essential anæmia is a decided and prolonged proportional diminution in the number of red blood corpuscles in the blood, which is not produced by loss of blood and nutritive fluids, like cachexia, nor by the destruction of the red blood corpuscles by means of poison. One of two things operates to produce an essential anæmia, viz., an insufficient formation and supply of red blood corpuscles on the part of the hæmatoblastic tissues, or a premature disintegration and destruction of the formed or partially formed cells.

Thus essential anæmias fall into two classes. The type of the first class is the so-called pernicious or progressive anæmia. In a few months this disease, in the face of all known remedies, reduces the blood, especially its hæmoglobin constituents, to or ro of its normal quantity. The nutrition of all the tissues is thereby impaired; the cardiac parenchyma undergoes fatty degeneration and death is caused by paralysis of the heart. In dissecting, we are astonished at the paradoxical condition of the bone marrow. Everywhere, even replacing the fat marrow of the long bones-the femur, tibia and humerus-we find an intensely red marrow containing numberless nucleated red blood corpuscles; in other words, an advanced state of development of those cells in which the blood is deficient. What is the meaning of this? Why was the formation of red blood corpuscles arrested just before completion? And why did they not enter into the blood? Pernicious anæmia is of rare occurrence. It is only found among the badly nourished of the poorer classes of society.

An anæmia called chlorosis, which is generally of a temporary